Improvement in bridges



l. M. GOODWIN.

Bridges. A f N0. 142,785. Patented'Septelpber16,1873.

W* fm .1w i

A. "Qq

T Q...) g* @Li I- N I WTNESSES- A INTENTOR.

. wz/Wg ffm/M NTTED STATES JOHN M. GOODWIN, OF NEW YORK, N. Y.

IMPROVEMENT IN BRIDGES.

Specification forming part of Letters Patent No. 142,785, dated September 16, 1873; application filed January 29, 1873.

To all whom it may concern:

Be it known that I, J OHN M. GOODWIN, of the city, county, and State of New York, have invented a new and useful Improvement in Bridges for Railways, Wagon-Roads, and for other purposes, of which the following is a specification, reference being had to the accompanyin g drawings, which form part of this specification, and in Which- Figure l represents a side elevation of a bridge embodying my invention, and Fig. 2 represents a plan of the same.

Wherever placed on said drawings the following letters of reference indicate the following-named parts of the bridge and its supports.

A A', abutments; P P', piers on abutments; G, principal girder; X, cross-beam; D D', supplementary girders, s, seat of cross-beam. E E' indicate the ends of the bridge. L, with arrows, indicates the direction of pressure and direction of motion of supposed load.

The obj ect of my said invention is to relieve the principal girders, chords, side Or middle trusses or beams of bridges, and girders, beams, or trusses used in structures other than bridges, of the action and effect of loads moving along or over them, technically known as rolling loads," and to cause the stress of any load passing along Or over, or distributed unequally upon, any bridge or structure in which said invention or device is used to act always in a direction nearly absolutely vertical, and practically vertical, upon one certain surface, as the seat s of the cross-beam X in Fig. l, or upon a certain pair Or line of similar surfaces, such as the lower flange or base of the cross-beam X covers in the principal girders G G in Fig. 2, or such as said cross-beam would cover were one or more additional principal girders lying parallel to G G' introduced in the construction of the bridge or other structure; and at the same time to cause the stress of such rolling loads to be brought upon such surface or surfaces by a gradual accumulation, the stress upon such surface or surfaces of the principal girder or girders acting at all times in a direction practically vertical, as aforesaid, and with a force always in proportion to the distance from the ends of the bridge E E', Fig.

1, at which any load, as L, Fig. 1, upon the supplementary girders aforesaid, may be, the said load being in this connection considered as passing from E toward O, the force only and not the character of such stress being changed by the changing of the position of the load, thereby removing from the principal girder or girders those undulatory and otherwise disintegrating disturbances of ber which are produced by the direct action of' rolling loads; and also to cause the stress of o any unequally-distributed load to be transmitted to the principal girder or girders aforesaid through the surface or surfaces, and in the direction, nearly and practically vertical, hereinbefore specified.

The object had in view, as above described, I arrive at by constructing my girder, or series of girders, or bridge, according to the principle, and essentially according to the plan, illustrated by the accompanying drawings, by reference to Fig. 1 of which it will be seen that the stress of a load, as L, with arrows, Fig. 1, passing from E toward O will be gradually, and in proportion to the progress of the load toward O, brought, through the medium of the supplementary girder D and of the cross-beam X, upon the surface s of the principal girder G, and upon said surface in a direction practically vertical; and, furthermore, that in passing from (l toward E' the stress of said load will be, by the operation of the supplementary girder D', gradually transferred from the principal girder G to the pier P', and that the entire stress of loads, however such loads may be distributed over the supplementary girders D D', will be brought, by the before-described operation of the several parts of the bridge,in a direction practically vertical upon the surface s of the principal girder G, it being understood that by the term entire stress77 I mean to indicate the entire stress that the principal girder G is called upon to support. When any part of the load is at any point on the supplementary girder D -for instance, between G andthe extremity of the bridge E-a portion of the stress, greater or less, as the load is nearer to or further from E, is communicated to the pier P.

In bridges whether for railways or for wagon roads, and in other structures of similar char- :Later Where it is desirable to use more than one principal girder, the cross-beam X may, if desired, be suspended beneath the principal girders G G, and directly below its position, as shown in the drawing, and the piers P P' being omitted, the supplementary girders D D D D muy lie with their upper surfaces flush with the upper surfaces 0i' the principal girders G G.

Vhat I claim is- The combination, in a bridge or other similer structure, of the principal girders G G', the supplementary girders D D D D', and the cross-beam X, or their equivalents, in connection With abutments A A', and piers or abutments P E or their equivalents, substantially as and for the purposes described.

JOHN M. GOODWIN.

Witnesses:

H. S. SAFFORD, GEO. B. HoY'r. 

